Article

Nucifora PG, Verma R, Lee SK, Melhem ER. Diffusion-tensor MR imaging and tractography: exploring brain microstructure and connectivity

Yonsei University, Sŏul, Seoul, South Korea
Radiology (Impact Factor: 6.21). 12/2007; 245(2):367-84. DOI: 10.1148/radiol.2452060445
Source: PubMed

ABSTRACT Diffusion magnetic resonance (MR) imaging is evolving into a potent tool in the examination of the central nervous system. Although it is often used for the detection of acute ischemia, evaluation of directionality in a diffusion measurement can be useful in white matter, which demonstrates strong diffusion anisotropy. Techniques such as diffusion-tensor imaging offer a glimpse into brain microstructure at a scale that is not easily accessible with other modalities, in some cases improving the detection and characterization of white matter abnormalities. Diffusion MR tractography offers an overall view of brain anatomy, including the degree of connectivity between different regions of the brain. However, optimal utilization of the wide range of data provided with directional diffusion MR measurements requires careful attention to acquisition and postprocessing. This article will review the principles of diffusion contrast and anisotropy, as well as clinical applications in psychiatric, developmental, neurodegenerative, neoplastic, demyelinating, and other types of disease.

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    • "The first magnetic resonance sequence able to measure diffusion coefficient in structures was developed in the early 80's (Wesbey et al., 1984), paving the way for a new, well-established imaging contrast for in vivo quantification of molecular diffusivity. Although a variety of sequences are now used to acquire diffusion weighted (DW) images, all DW sequences include two equal and opposing motion-probing gradients (Nucifor et al., 2007). The acquired signal from a voxel will exponentially decay as function of a parameter b which determines the strength and duration of the diffusion gradients and essentially represents the measurement's sensitivity to water diffusion . "
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    • "These features have been attributed to the disruption of the underlying structures of neural networks [Ellison-Wright and Bullmore , 2009; Kubicki et al., 2007]. Diffusion MRI is a technique that is capable of detecting the microstructural integrities of the axonal fibers of the white matter [Basser et al., 2000; Nucifora et al., 2007] and has revealed disruptions of these networks in vivo [Kanaan et al., 2005]. Numerous diffusion MRI studies have reported abnormal white matter regions in patients with schizophrenia and also in first-episode, drug-na€ ıve, and high-risk patients [Lee et al., 2013; Peters et al., 2008; Samartzis et al., 2014]. "
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    • "ivity . Of the extensive cellular responses produced by ischemia , those considered most likely to affect the diffusion properties of water are those that in - volve morphological tissue changes such as necrosis , astrogliosis , loss of myelin , loss of axonal neurofilaments or cellular inflammation ( i . e . microglial / macrophage activation ) ( Nucifora et al . , 2007 ; Zhang et al . , 2012 ) . Our group and others have shown that corticospinal tract DTI al - terations are strongly correlated with motor outcome in children with perinatal stroke ( Hodge , 2013 ; Roze et al . , 2012 ; van der Aa et al . , 2011 ) . However the progression of DTI changes and whether there are differences between the evol"
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